Cooperative effects in the substrate specificity of the complement protease C1s

Area of Science:

• Biochemistry
• Immunology
• Enzymology

Background:

• The complement system is crucial for immunity but implicated in inflammatory diseases.
• Understanding protease substrate specificity is vital for drug development and disease research.

Purpose of the Study:

• To investigate the substrate specificity of the C1s protease.
• To explore potential cooperativity within the C1s protease active site.
• To evaluate the efficacy of factorial design in analyzing protease active sites.

Main Methods:

• Utilized a combinatorial approach to study C1s protease substrate specificity.
• Employed a factorial design to create a peptide panel for enzyme analysis.
• Analyzed interactions between S4, S1', and S3' subsites in the C1s protease active site.

Main Results:

• Demonstrated pronounced cooperativity between the S4 and S1' subsites of C1s protease.
• Identified weaker cooperativity between the S1' and S3' subsites.
• Showed that factorial design can effectively reveal cooperativity in protease active sites, unlike positional scanning.

Conclusions:

• Enzyme active site cooperativity can confound traditional substrate specificity analyses.
• Factorial design is a promising methodology for characterizing protease active site dynamics.
• Findings advance the understanding of C1s protease function and inflammatory disease mechanisms.